The present invention refers to a take-up reel for rolling and unrolling winding material such as strips, wires and the like, and in particular to a take-up reel of the type having a barrel with two disk-like end flanges which are provided at their outer end faces with profile-forming bumps.
In general, a take-up reel of this type is made of shock resistant plastic material and of H-shaped configuration in longitudinal section. The lateral end flanges retain the reeled winding material upon the barrel and serve as abutment for co-rotating support skirts of a winding machine.
Conventional reels of this type have bumps in form of radial ribs which are spaced from each other at a small angular distance. The ribs reinforce in particular the end flanges to lessen a flexure thereof. Moreover, these end flanges are suitably dimensioned to withstand centrifugal forces in particular during initial winding when these centrifugal forces are very high. The initial winding speed ranges up to for example 4,000 rpm.
Practice has shown that the use of such radial ribs subjects the end flanges to stress concentrations in the area of the juncture to the barrel when the take-up reel is dropped and impacts on the rim of one end flange e.g. during a stress test or during inadvertent fall, resulting in fine tearings which are not visible to the naked eye. Therefore, for safety reasons, a reuse of take-up reels of this type is not advised. Practice has also shown that at extremely high speeds parts of the end flanges are thrown off.